Diabetes mellitus is a major public health problem in India and worldwide. One of its most common and feared complications is Diabetic foot infections (DFIs), which, if neglected, very often terminate in limb amputation. Limb-threatening DFIs are usually polymicrobial. Proper management of these infections requires appropriate antimicrobial selection based on culture and antimicrobial susceptibility results; however, initial management comprises empirical antimicrobial therapy. Knowledge of likely etiologic agents can help guide this decision and result in limb salvage.
To study the common clinical presentation of DFIs, isolate the organisms responsible and to determine the antimicrobial susceptibility pattern of the isolates.
During the period from Nov 2011 to Oct 2013, pus and tissue samples were taken from the affected feet of 60 DFI patients and subjected to smear microscopy, aerobic and anaerobic culture. The antimicrobial susceptibility testing of the isolates was done by Kirby Bauer disc diffusion method.
Most of the study patients presented with advanced clinical features such as gangrene (38.3%), abscess (38.3%) and limb cellulitis (18.3%). Polymicrobial foot infection was present in 31 cases (51.7%). Aerobes were predominantly isolated (93.6%). Overall, the most common isolate was Staphylococcus aureus (36.4%). Gram positive organisms (54.5%) were isolated more frequently than gram negative organisms (45.5%). Gram positive isolates showed 100% sensitivity towards linezolid. All the major groups of organisms showed high sensitivity towards third generation cephalosporins. High sensitivity towards meropenem, and other newer generation antimicrobials including piperacillin-tazobactum, tigecycline and colistin was noted among the gram negative isolates.
Proper education and awareness about DFIs, aggressive antimicrobial therapy and foot care can reduce the associated morbidity and help in limb salvage. Initial empirical therapy with a broad spectrum antimicrobial such as third generation cephalosporins is recommended. With several reported advantages, including excellent efficacy, good soft tissue penetration and tissue concentrations even in the presence of limb ischemia, significantly shorter length of hospital stay, decreased parenteral antibiotic duration and higher early discharge rates, ability to institute oral-only therapy on an out-patient basis, and consequent cost-effectiveness, linezolid has emerged as a good treatment choice in pure gram positive infections, especially against multidrug resistant strains, and in chronic, recalcitrant cases.
Diabetic foot infections, DFI, polymicrobial, linezolid
